Biology 1 of 39
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9-1 Chemical Pathways Food serves as a source of raw materials for the cells in the body and as a source of energy. Animal Cells Animal Mitochondrion Plant Plant Cells 3 of 39
Both plant and animal cells carry out the final stages of cellular respiration in the mitochondria. Animal Cells Outer membrane Intermembrane space Mitochondrion Inner membrane Matrix Plant Cells 4 of 39
Chemical Energy and Food Chemical Energy and Food One gram of the sugar glucose (C 6 H 12 O 6 ), when burned in the presence of oxygen, releases 3811 calories of heat energy. A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius. 5 of 39
Overview of Cellular Respiration What is cellular respiration? 6 of 39
Overview of Cellular Respiration Electrons carried in NADH Pyruvic acid Electrons carried in NADH and FADH 2 Glucose Glycolysis Cytoplasm Mitochondrion 7 of 39
Overview of Cellular Respiration Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen. 8 of 39
Overview of Cellular Respiration The equation for cellular respiration is: 6O 2 + C 6 H 12 O 6 6CO 2 + 6H 2 O + Energy oxygen + glucose carbon dioxide + water + Energy 9 of 39
Overview of Cellular Respiration Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place in the mitochondria. Glycolysis Cytoplasm Mitochondrion 10 of 39
Glycolysis What happens during the process of glycolysis? 11 of 39
Glycolysis ATP Production At the beginning of glycolysis, the cell uses up 2 molecules of ATP to start the reaction. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2 Pyruvic acid 12 of 39
Glycolysis When glycolysis is complete, 4 ATP molecules have been produced. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2 Pyruvic acid 13 of 39
Glycolysis This gives the cell a net gain of 2 ATP molecules. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2 Pyruvic acid 14 of 39
Glycolysis NADH Production One reaction of glycolysis removes 4 high-energy electrons, passing them to an electron carrier called NAD +. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2NAD + 2 Pyruvic acid 15 of 39
Glycolysis Each NAD + accepts a pair of high-energy electrons and becomes an NADH molecule. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2NAD + 2 2 Pyruvic acid 16 of 39
Glycolysis The NADH molecule holds the electrons until they can be transferred to other molecules. 2 ATP 2 ADP 4 ADP 4 ATP 2NAD + 2 2 Pyruvic acid To the electron transport chain 17 of 39
Glycolysis The Advantages of Glycolysis The process of glycolysis is so fast that cells can produce thousands of ATP molecules in a few milliseconds. Glycolysis does not require oxygen. 18 of 39
Fermentation Fermentation When oxygen is not present, glycolysis is followed by a different pathway. The combined process of this pathway and glycolysis is called fermentation. Fermentation releases energy from food molecules by producing ATP in the absence of oxygen. 19 of 39
Fermentation During fermentation, cells convert NADH to NAD + by passing high-energy electrons back to pyruvic acid. This action converts NADH back into NAD +, and allows glycolysis to continue producing a steady supply of ATP. Fermentation does not require oxygen it is an anaerobic process. 20 of 39
Fermentation What are the two main types of fermentation? 21 of 39
Fermentation Alcoholic Fermentation Yeasts and a few other microorganisms use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastes. The equation for alcoholic fermentation after glycolysis is: pyruvic acid + NADH alcohol + CO 2 + NAD + 22 of 39
Lactic Acid Fermentation Fermentation In many cells, pyruvic acid that accumulates as a result of glycolysis can be converted to lactic acid. This type of fermentation is called lactic acid fermentation. It regenerates NAD + so that glycolysis can continue. The equation for lactic acid fermentation after glycolysis is: pyruvic acid + NADH lactic acid + NAD + 23 of 39
Fermentation The first part of the equation is glycolysis. 24 of 39
Fermentation The second part shows the conversion of pyruvic acid to lactic acid. 25 of 39
9-1 Continue to: - or - Click to Launch: 26 of 39
9-1 The raw materials required for cellular respiration are a. carbon dioxide and oxygen. b. glucose and water. c. glucose and oxygen. d. carbon dioxide and water. 27 of 39
9-1 Glycolysis occurs in the a. mitochondria. b. cytoplasm. c. nucleus. d. chloroplasts. 28 of 39
9-1 The net gain of ATP molecules after glycolysis is a. 3 ATP molecules. b. 2 ATP molecules. c. 3 pyruvic acid molecules. d. 4 pyruvic acid molecules 29 of 39
9-1 Fermentation releases energy from food molecules in the absence of a. oxygen. b. glucose. c. NADH. d. alcohol. 30 of 39
9-1 The first step in fermentation is always a. lactic acid production. b. the Krebs cycle. c. glycolysis. d. alcohol production. 31 of 39
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